Carbonyl Groups in Cellulose

The quantitation of carbonyl groups in cellulose was so far limited to the measurement of the total carbonyl content by different methods, which are summarized in Table 1. 

Table 1 Classical methods for determination of carbonyl groups in cellulose...

J. Rdhrhng, A. Potthast, T. Rosenau, T. Lange, G. Ebner, H. Sixta, and P. Kosma, A novel method for the determination of carbonyl groups in cellulosics by flourescence labeling. 1. Method development, Biomacromolecules, 3 (2002) 959-968. 

The main causes for the formation of carbonyl and carboxyl groups in cellulose are isolation and purification procedures besides natural aging. This applies in particular to cellulosic pulps from wood, which has undergone a number of processing steps to be freed from lignin, hemicelluloses, and extractives. 

The reducing end groups in cellulose are the only naturally occurring carbonyl functionalities in this material. Cellulose from Acetobacter xylinum [43] contains an amount of carbonyl groups which corresponds approximately to the number of reducing end groups, and can be considered as rather genuine material. 

Only second to carbonyl groups, carboxyls are a very important oxidized function in celluloses (Scheme 7). Whereas hemicelluloses inherently contain a high number of different acid groups, carboxyl groups in cellulose are artifi-... 

Photoinduced graft copolymerization of cellulose derivatives especially containing carbonyl groups in the absence of a photosensitizer, has been investigated. Grafting of methyl methacrylate onto dialdehyde and dicarboxyl celluloses proceeded more easily than onto monocarboxyl cellulose. The grafting efficiency of the former two samples attained to 95-100%. 

The experimental evidence obtained has shown that the reactivity of the estos of the aromatic and aliphatic carboxylic acids under study in the reaction of alcoholysis with cellulose changes substantially with changes in the chemical constitution of the acyl radical. According to existing con<%ptions (52), the alcoholysis of esters in the presence of an alkaline catalyst at the rate-determining step involves the attack of the alkoxy ion on the carbon atom erf the carbonyl group in the case of... 

Pyrolysis of cellulose at 170° in an atmosphere of nitrogen or oxygen has been studied. At this temperature, heating under nitrogen had little effect, but, under oxygen, there was a primary oxidation effect in the amorphous regions. The rates of production of carbon dioxide, carbon monoxide, and water, and the formation of carboxyl and carbonyl groups in the residue, were measured. 

Borohydride reduction at pH 9-9.5 has been developed by Lindberg and coworkers as a stoichiometric method of determining carbonyl groups in sugars and in periodate-oxidized cellulose it has also been applied to... 

D. Horton and D. M. Clode, Synthesis of the 6-aldehydo derivative of cellulose, and a mass spectrometric method for determining position and degree of substitution by carbonyl groups in oxidzed polysaccharides, Carbohydr. Res., 19 (1971) 329-337. 

The reactions of NaOH with cellulose in natural fiber yielded cellulose-ONa compound and removed impurities from the fiber surface [11,12]. This is confirmed by the FTIR spectroscopic analysis as shown in Figure 14.1. The FTIR spectrum of the raw wood clearly shows the absorption band in the region of3407 cm, 2917 cm and 1736 cm due to O-H, C-H and C = O stretching vibration respectively. These absorption bands are due to hydroxyl groups in cellulose, carbonyl groups of acetyl ester in hemi-cellulose and carbonyl aldehyde in lignin. 

From the studies of blends of PCL with the several cellulose esters, Vazquez-Torres and Cruz-Ramos [121] suggested that there is some interaction between hydroxyl and carbonyl groups in the different polymers but features did not vary systematically with hydroxyl content and other factors. 

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